Strain on the framework of a mandibular free-end saddle partial denture under load.

Strairra were determined in a typical maridibiilar partial denture metal framework of the free-end saddle type. The overall strain patterirs were det,ermined using a brittle lacquer coating t,echriiqrie and loads were a.pplied vertically to positions on the saddles. The resulk from the coating study indicated the area of high strain were jrist anterior and posterior t,o t,he finishing lines. Strain gages were attached to posit,ions anterior and posterior to t,he finishing lines and the strain was measured at, t,hese positions when the saddles were loaded either at a posterior or anterior posit,ion at, intervals of 2 Ib up t,o 20 Ib. When a st,at,ic load of 20 Ib was applied to the posterior of t,he left aaddle n st,rairi of 7.50 p in./in. was obtained, which for the alloy used was eynivalent t,o a st>ress of 22,200 lb/in.2. The amount of st,rairi observed was a funct,ioii of the leirgt8h of t,he saddle, the biilk of the framework, the relation of the site of the gage to the position of loading, the presence of an indirect retainer, arid t,he posit,ioii of the fiilcriini for the loading conditions used.